What does 'hi' means?

[EchoingWhisper]

Lo and Hi ISO is done with software. Both usually entail a significant loss of dynamic range because it is essentially faked ISO.

Normal, or base ISO is done with amplifiers on the image sensor.

Thanks.

 

[Patrice]

Depending on the camera you are using, it may be better to shoot with a higher iso, or on some new models (nikon d7000 for example) it may be better to shoot at iso 100 or 200 and then adjust the image on the computer instead (so that highlights aren't clipped like they would have been had the camera done the processing).

Where did you get this piece of information?

 

[Helen B]

When a Nikon camera's performance, as tested, does NOT MEET the official ISO performance criteria, Nikon then specifies the extended ISO capability levels or settings using the "Hi" nomenclature. Nikon is not trying to bull-chit its users....so they use a different way of referencing how high the gain is, in an "approximate" ISO-equivalence in the areas on either side of the official, tested range. There is also Lo. on some camera models. In the Lo- mode, slightly compromised dynamic range is a typical "feature" that users can look forward to.

Exactly.

The way ISO speed is defined does not really set an upper limit. An ISO speed is the EI (exposure index) used for an exposure that meets the criteria set out in the relevant ISO standard.

 

[rsbones]

Depending on the camera you are using, it may be better to shoot with a higher iso, or on some new models (nikon d7000 for example) it may be better to shoot at iso 100 or 200 and then adjust the image on the computer instead (so that highlights aren't clipped like they would have been had the camera done the processing).

Where did you get this piece of information?

There has been lots of discussion about this issue on photography forums over the last year. Here's probably a good place to start:

The role of ISO in exposure and how it applies to photography. [Page 1]: Open Talk Forum: Digital Photography Review


The role of ISO in exposure and how it applies to photography (part 2) [Page 1]: Open Talk Forum: Digital Photography Review


and here is an example of how using low ISO on some cameras produces better results:

http://new.dpreview.com/forums/read.asp?forum=1022&message=37235114

 

[MTVision]

Depending on the camera you are using, it may be better to shoot with a higher iso, or on some new models (nikon d7000 for example) it may be better to shoot at iso 100 or 200 and then adjust the image on the computer instead (so that highlights aren't clipped like they would have been had the camera done the processing).

Where did you get this piece of information?

There has been lots of discussion about this issue on photography forums over the last year. Here's probably a good place to start:

The role of ISO in exposure and how it applies to photography. [Page 1]: Open Talk Forum: Digital Photography Review


The role of ISO in exposure and how it applies to photography (part 2) [Page 1]: Open Talk Forum: Digital Photography Review


and here is an example of how using low ISO on some cameras produces better results:

Re: sensor gain vs underexposure: Olympus SLR Talk Forum: Digital Photography Review

Wouldn't low ISO usually produce better results - as long as the image is properly exposed?

 

[rsbones]

Define "properly exposed". The example shown in my link above shows a scene photographed with two settings:

1/30, f2.0, ISO 100
1/30, f2.0, ISO 6400

Most people would traditionally say that only the second one was "properly exposed". In either case, the exact same amount of light hit the sensor of course. And with cameras like the D7000 that have very flat read noise curves, one can set the camera at ISO 100, capture approximately 14 stops worth of dynamic range, instead of setting it at 6400 where you'll only get about 7 stops (the camera will "clip" highlights). The jpg displayed on your on camera lcd will be terribly dark - perhaps totally black. But when you import your raw file into, say, Lightroom software and push the exposure 6 stops (while protecting highlights), the photo will reach the brightness you would have had at ISO6400, won't have blown highlights, and will have suffered no noise penalty.

In other words, with these types of sensors, in low light situations it's possible to forget about ISO when considering "exposure": leave it at iso100, pick the aperture you want for the DOF you want, and set the shutter speed you want to control motion, and then as long as you are within 6 or 8 stops, you can develop the image correctly on the computer instead of asking the camera to process it first (which is what changing the ISO on camera does, but in a less sophisticated manner than the computer can do).

 

[Destin]

Define "properly exposed". The example shown in my link above shows a scene photographed with two settings:

1/30, f2.0, ISO 100
1/30, f2.0, ISO 6400

Most people would traditionally say that only the second one was "properly exposed". In either case, the exact same amount of light hit the sensor of course. And with cameras like the D7000 that have very flat read noise curves, one can set the camera at ISO 100, capture approximately 14 stops worth of dynamic range, instead of setting it at 6400 where you'll only get about 7 stops (the camera will "clip" highlights). The jpg displayed on your on camera lcd will be terribly dark - perhaps totally black. But when you import your raw file into, say, Lightroom software and push the exposure 6 stops (while protecting highlights), the photo will reach the brightness you would have had at ISO6400, won't have blown highlights, and will have suffered no noise penalty.

In other words, with these types of sensors, in low light situations it's possible to forget about ISO when considering "exposure": leave it at iso100, pick the aperture you want for the DOF you want, and set the shutter speed you want to control motion, and then as long as you are within 6 or 8 stops, you can develop the image correctly on the computer instead of asking the camera to process it first (which is what changing the ISO on camera does, but in a less sophisticated manner than the computer can do).

If you push a black image six stops in Lightroom, you're going to introduce a TON of noise. Hate to burst your bubble.

You are ALWAYS better off properly exposing in camera, because upping the exposure on an underexposed image in post adds MORE noise than increasing the iso, especially with cameras as good in low light as the D7k.

 

[rsbones]

If you push a black image six stops in Lightroom, you're going to introduce a TON of noise. Hate to burst your bubble.

You are ALWAYS better off properly exposing in camera, because upping the exposure on an underexposed image in post adds MORE noise than increasing the iso, especially with cameras as good in low light as the D7k.

Please either try it yourself, or go to the threads linked and see the results others have gotten on their tests. Look at the images of the building at night: the iso6400 shot has blown highlights, as you'd expect - but the iso100 shot does not because you can protect them when adjusting the image on the computer, taking advantage of capturing a much expanded dynamic range, all without introducing more noise. This is the advantage these new sensors provide and it requires a new way of thinking about iso.

http://www.sensorgen.info lists all the data for various cameras so you can see which current sensors have this flat read noise feature and which don't, what the dynamic range at each iso setting is, etc.

 

[EchoingWhisper]

If you push a black image six stops in Lightroom, you're going to introduce a TON of noise. Hate to burst your bubble.

You are ALWAYS better off properly exposing in camera, because upping the exposure on an underexposed image in post adds MORE noise than increasing the iso, especially with cameras as good in low light as the D7k.

Please either try it yourself, or go to the threads linked and see the results others have gotten on their tests. Look at the images of the building at night: the iso6400 shot has blown highlights, as you'd expect - but the iso100 shot does not because you can protect them when adjusting the image on the computer, taking advantage of capturing a much expanded dynamic range, all without introducing more noise. This is the advantage these new sensors provide and it requires a new way of thinking about iso.

Sensorgen - digital camera sensor data lists all the data for various cameras so you can see which current sensors have this flat read noise feature and which don't, what the dynamic range at each iso setting is, etc.

Can you do some tests? I'm not really good at creating these tests. Your claims seems reasonable.

 

[Destin]

Ill do some formal tests, but I'm telling you, I know from experience that it won't work.

I tried the whole "underexpose and repair in post thing" while shooting high school football this year, in order to achieve a higher shutter speed. It didn't turn out well. However, as you wish I'm going to conduct some formal tests right now. Granted I'm shooting a d80, so 1600 is my highest native ISO and will have to do.

 

[Destin]

OK, test complete, and I'm gonna go out on a limb and say I'm correct. Here are my 2 shots, and 2 crops from each. All photos were taking in RAW, so in camera NR was not a factor.

Let's start with the "properly exposed" shots, taken at iso 1600. ALL other settings remained the same. The only thing done differently in camera was changing the iso.

Post Processing: For the shots taken at 1600, all I did in post was bring the exposure down -.14 in LR to correct a slightly off exposure in camera, and slide the luminance noise reduction slider up to 35. Also converted from raw to .jpg upon export for all photos.

crop 1 @1600:

Crop 2 @1600

For the following iso 100 shots I bumped the exposure up 3.86 stops, to bring it to the exact same level as the shots taken at 1600. I then had to adjust the contrast, saturation, vibrance, and black levels in order to repair butchered colors from underexposing 4 stops in camera. I then upped the luminance NR slider to 55, which seemed to be as far as I could push it without it looking like a watercolor painting.

Here are the shots taken at 1600 and then "repaired" in post:

crop 1 @iso 100:

crop 2 @iso 100:

My conclusions:
The only positive thing I can see about underexposing by 4 stops in camera, and then repairing it in post, is that you don't need to worry about blowing highlights. By looking at these images, you can clearly see that it introdces MORE shadow noise than the properly exposed image coming SOOC (and these were done with a camera that's 2 generations old. This would be MUCH more pronounced in newer generation cameras with better high iso performance). You can also clearly see that the image taken at 1600 was able to better preserve dynamic range than the one taken at 100 and then pushed in post.

This test has simply reinforced what I already knew to be true. Post processing cannot replace getting it right in camera.

 

[rsbones]

No one is claiming all cameras can be used in this fashion. The technology is still evolving in that direction. I can't find the info for the D80 sensor - it may not work in the fashion the D7000 and other cameras using the latest (sony made) sensors do. I don't own a D7000 either, or I'd post my own tests. But here is another test and interesting discussion:

D7000: an ISO less camera [Page 1]: Nikon D90 - D40 / D7000 - D3000 Forum: Digital Photography Review

 

[Destin]

If you push a black image six stops in Lightroom, you're going to introduce a TON of noise. Hate to burst your bubble.

You are ALWAYS better off properly exposing in camera, because upping the exposure on an underexposed image in post adds MORE noise than increasing the iso, especially with cameras as good in low light as the D7k.

Please either try it yourself, or go to the threads linked and see the results others have gotten on their tests. Look at the images of the building at night: the iso6400 shot has blown highlights, as you'd expect - but the iso100 shot does not because you can protect them when adjusting the image on the computer, taking advantage of capturing a much expanded dynamic range, all without introducing more noise. This is the advantage these new sensors provide and it requires a new way of thinking about iso.

Sensorgen - digital camera sensor data lists all the data for various cameras so you can see which current sensors have this flat read noise feature and which don't, what the dynamic range at each iso setting is, etc.

Bull. Crap. Just because you are preserving the blown highlights, does NOT mean you have captured a greater dynamic range. You underexposed by 6 stops in the example, so CLEARLY your highlights won't be blown. Where the theory falls flat, is that by underexposing the image by 6 stops, you just lost the majority of your shadow detail, and it cannot be recovered in post, because it was NEVER recorded in the first place. This is a classic HDR scenario. You need a greater dynamic range than what current sensor technology can provide, and there is no way to cheat that using a single exposure.

 

[manaheim]

Define "properly exposed". The example shown in my link above shows a scene photographed with two settings:

1/30, f2.0, ISO 100
1/30, f2.0, ISO 6400

Most people would traditionally say that only the second one was "properly exposed". In either case, the exact same amount of light hit the sensor of course. And with cameras like the D7000 that have very flat read noise curves, one can set the camera at ISO 100, capture approximately 14 stops worth of dynamic range, instead of setting it at 6400 where you'll only get about 7 stops (the camera will "clip" highlights). The jpg displayed on your on camera lcd will be terribly dark - perhaps totally black. But when you import your raw file into, say, Lightroom software and push the exposure 6 stops (while protecting highlights), the photo will reach the brightness you would have had at ISO6400, won't have blown highlights, and will have suffered no noise penalty.

In other words, with these types of sensors, in low light situations it's possible to forget about ISO when considering "exposure": leave it at iso100, pick the aperture you want for the DOF you want, and set the shutter speed you want to control motion, and then as long as you are within 6 or 8 stops, you can develop the image correctly on the computer instead of asking the camera to process it first (which is what changing the ISO on camera does, but in a less sophisticated manner than the computer can do).

Bones, you've responded 2x on this thread and in both cases I'm almost completely certain that your information is totally off.

I'm not going to go research it because I'm busy with something else, but I'll go out on a limb and say that switching to different ISO has no noteworthy impact in dynamic range at all... and CERTAINLY not a 2x impact. I'm pretty certain there isn't a camera on the market that isn't capable of capturing "14 stops of light" without software tricks such as "HDR".

Also, no one is going to say that any particular setting for ISO on a camera is properly exposed without knowing the scene in question. I say this merely as an additional emphasis that you're probably not quite as informed as you may think.

 

[manaheim]

Ok, I couldn't help but do a little research...

It looks like there ARE some effects...

Understanding Dynamic Range in Digital Photography

I haven't read the whole thing yet, but scanning around it looks like "some", but not 7->14.

I may be wrong... I'll have to read it in detail later.

If I'm wrong: I'm sorry.
If I'm partially wrong: I'm partially sorry.
If I'm not wrong: Please add additional snark to my previous post.

Thank you.